//package datagram;
//
//import java.io.IOException;
//import java.net.DatagramPacket;
//import java.net.DatagramSocket;
//import java.net.SocketException;
//import java.nio.charset.StandardCharsets;
//
//public abstract class UdpEchoSever {
//    private DatagramSocket socket = null;
//    private String request;
//
//    public UdpEchoSever(int port) throws SocketException {
//        socket = new DatagramSocket(port);
//    }
//    //通过start启动服务器的核心流程
//    public void start() throws IOException {
//        System.out.println("服务器启动!");
//        while(true){
//            //此处通过"死循环"不同的处理客户端的请求
//            //1.读取客户端的请求并解析
//            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
//            socket.receive(requestPacket);
//            //上述数据是byte形式展现的
//            //转换成字符串才好处理
//            String request = new String(requestPacket.getData(),0,requestPacket.getLength());
//            //2.根据请求计算响应
//            String response = process(request);
//            //3.把响应写回客户端
//            DatagramPacket responsePocket = new DatagramPacket(response.getBytes(),response.getBytes().length,
//                    requestPacket.getSocketAddress());
//            socket.send(responsePocket);
//            //4.打印日志
//            System.out.printf("[%s:%d] req = %s,resp = %s\n",requestPacket.getAddress(),requestPacket.getPort(),
//                    request,response);
//        }
//    }
//    private String process(String request){
//        return request;
//    }
//
//    public abstract String process(String request);
//
//    public static void main(String[] args) throws IOException {
//        UdpEchoSever sever = new UdpEchoSever(9090);
//        sever.start();
//    }
//}
//
